1. Field of the Invention
The present invention relates to apparatus for use in oil and gas wells where a producing zone produces both hydrocarbon fluids (such as gas) and water and in which the water is disposed in a downhole disposal zone without pumping to the surface.
2. Background Description
Oil and gas and other minerals are found in subterranean strata or stratum, or layers. To produce the wanted products, wells are drilled from the surface down through those strata. These strata layers that are sought contain, for example, hydrocarbon fluids such as gas which may be produced to the surface and burned to heat homes, factories, etc. or used in various chemical processes. These wells are lined with heavy steel pipe called "well casing." They are usually cemented in place so that fluids cannot escape or flow along the space between the casing and the borehole wall.
Unfortunately, essentially all gas producing stratum contains unwanted material such as salt water or brine which is produced into the well bore along with the gases. It is a common practice to produce the hydrocarbon fluids and the salt water to the surface where the water is separated out. The water is very frequently then injected through another well which has been drilled to a disposal zone which is deep within the earth. This method is quite expensive inasmuch as it requires the drilling of an additional well.
In some published methods, the salt water is separated downhole in the casing from the hydrocarbon fluid. The mixture of the hydrocarbon fluid and water is forced through perforations of the wall of the casing into the interior of the casing where the water is separated out by gravity inasmuch as it is heavier than the hydrocarbon fluid. In some cases the water disposal zone may be located beneath the producing zone. Sometimes in such cases the operator will install a downhole pump so that the separated water may be forced into the lower disposal zone as shown in U.S. Pat. No. 3,167,125.